Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.20 (alpha-glucosidase)
 4,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The complete nucleotide sequences of four genes and one open reading frame (ORF1) adjacent to the streptokinase gene, skc, from Streptococcus equisimilis H46A were determined. These genes are encoded on the opposite DNA strand to skc and are arranged as follows: dexB-abc-lrp-skc-ORF1-rel. The dexB gene, coding for an alpha-glucosidase (M(r) 61,733), and abc, encoding an ABC transporter (M(r) 42,080), are similar to the dexB and msmK genes, respectively, from the multiple sugar metabolism operon of S. mutans. The lrp gene specifies a leucine-rich protein (M(r) 32,302) that has a leucine-zipper motif at its C-terminus. The function of the Lrp protein is not known but appeared to be detrimental when overexpressed in Escherichia coli. Although lrp appears not to be an essential gene, as judged by plasmid insertion mutagenesis, it is conserved in all streptococcal strains carrying a streptokinase gene. The rel gene showed significant homology to the E. coli relA and spoT genes involved in the stringent response to amino acid deprivation. Multiple alignment of the amino acid sequences of Rel (M(r) 83,913), RelA and SpoT revealed 59.4% homology of the primary structures. Northern hybridization analyses of the genes in the skc region showed skc to be transcribed most abundantly. In addition to transcripts for skc, monocistronic mRNAs were detected for all three genes divergently transcribed from skc. Although there was also some read-through transcription from lrp into abc, and from abc into dexB, the transcription pattern suggests a high degree of transcriptional and functional independence not only of skc but also abc and dexB. Prominent structural features in intergenic regions included a static DNA bending locus located upstream and a putative bidirectional transcription terminator downstream of skc.
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PMID:Genetic organization of the streptokinase region of the Streptococcus equisimilis H46A chromosome. 823 96

The maltose degradation operon containing genes encoding maltose phosphorylase mapA and phosphoglucomutase pgmA from Lactobacillus sanfranciscensis DSM20451T were cloned and expressed in Escherichia coli. These genes represent the first genetic data available for this species beyond taxonomic classification. MapA encodes a 754-amino acid polypeptide representing maltose phosphorylase, MapA, with a calculated molecular mass of 85.7 kDa. Comparative sequence analysis showed that mapA is of a new type distinct from other alpha-glucosidase genes sequenced so far. Putatively, pyridoxal 5'-phosphate is required as cofactor. The deduced amino acid sequence of pgmA shows an overall similarity of 39% to the phosphoglucomutase of Lactococcus lactis. pgmA is separated by a single nucleotide from the preceding mapA gene indicating effective translation by translational coupling. Upon subcloning mapA was heterologously expressed in E. coli. Additionally, upstream of the maltose-degrading operon ORF1 and ORF2 are located in the opposite direction. These genes show homology to fabZ and accB from E. coli and Bacillus subtilis, respectively, both involved in fatty acids biosynthesis.
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PMID:Maltose metabolism of Lactobacillus sanfranciscensis: cloning and heterologous expression of the key enzymes, maltose phosphorylase and phosphoglucomutase. 985 Oct 37

High-copy-number amplification of the AUD1 element is frequently associated with the large chromosomal deletions responsible for genetic instability in Streptomyces lividans TK64. Five ORFs were found in a 7 kb region directly adjacent to AUD1. The putative products of ORF1, ORF2 and ORF3 showed similarities to ATP-binding cassette (ABC) sugar transporters, the deduced protein sequence of ORF4 displayed similarities to alpha-glucosidases whilst no homology to proteins with known functions was found for ORF5. ORF4 (renamed aglA) was expressed in Escherichia coli and the protein purified and characterized. An alpha-glucosidase activity was detected using the synthetic alpha-glucoside p-nitrophenyl alpha-D-glucopyranoside. Of the many oligosaccharides tested, only sucrose was hydrolysed at a measurable rate [specific activity 32.4 units (mg protein)(-1)] but no growth of S. lividans TK64 on sucrose was observed. A strain in which aglA was disrupted showed the same low alpha-glucosidase activity as strain TK64 and in both strains no stimulation of activity was seen by sucrose, trehalose or maltose; dextrin increased alpha-glucosidase activity about 10-fold. This probably resulted from induction of a second alpha-glucosidase-encoding gene. The AUD1 element contains three 1 kb repeats which encode DNA-binding proteins necessary for high-frequency amplification. In strains with a unique 1 kb repeat, disruption of the repeat led to a significant increase in the alpha-glucosidase activity. These results strongly suggest that the 1-kb-repeat-encoded proteins of AUD1 have a dual function: they are the repressors of the agl genes and they promote amplification of AUD1.
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PMID:The 1-kb-repeat-encoded DNA-binding protein as repressor of an alpha-glucosidase operon flanking the amplifiable sequence AUD1 of Streptomyces lividans. 1078 51